Increased pressure to develop renewable energy resources, such as wind, may create a negative impact on the Hill Country bat populations. A dearth of information regarding the significance of wind energy development’s impact on the area’s migrating bat and bird populations is a major concern among scientists and non-governmental organizations. Wind facilities are being constructed in Texas without regulations and largely without environmental impact studies in place to insure minimal impact on the ecological systems in Texas and other states. These messages were articulated by Dr. Ed Arnett of Bat Conservation International of Austin at a nature series program on June 9 sponsored by the Friends of the Fredericksburg Nature Center.
Dr. Arnett has studied bats for more than fifteen years and for the past five years has led research efforts on bats and wind energy development. He currently serves on a number of national committees on wind energy and wildlife impact. For more information on bat studies, please visit the Bat Conservation International’s website: www.batcon.org.
Friends’ president Bill Lindemann opened the meeting by presenting a few statistics about Brazilian (Mexican) free-tailed bats, a major component in the Hill Country ecosystems. Lindemann stated that the estimated 100,000,000 bats that reside in caves in Central Texas during the summer months consume 1,000 tons of insects daily, which saves millions of dollars annually in agricultural control of destructive insects on crops. Their presence in our area also draws approximately 100,000 tourists to Texas annually, and the Congress Avenue Bridge bats in Austin alone generate millions of tourist dollars to the city’s economy.
The bats emerge from a number of other known locations in the Hill Country including the Old Tunnel Wildlife Management Area in northwest Kendall County, the James River Bat Cave in southwest Mason County and the Davis Cave in northeast Blanco County.
Dr. Arnett presented information on wind development impacts on different groups of birds and bats, building the case that the wind turbines do cause mortality in these flying animal populations. Construction of wind energy facilities is a relatively recent development, and most information from studies conducted by the wind energy development companies has not been released to the public. Funding of impact studies has been slow to develop, leaving scientists and public officials with limited data to draw conclusions regarding the severity of the problem, assess the impact and develop regulations.
Based on data from other states and Canada, the mortality rate of bats exceeds that of birds; the higher tolls occurring in the fall migration seasons. Data from Oklahoma indicated spring deaths involved pregnant female Brazilian free-tailed bats, which is considered troubling because of the low reproduction rates of bats. One of the factors in mortality studies is the number of dead bats removed by scavengers prior to the study counts. There is a critical need for systematic studies to understand the variables involving site location, effect of scavengers, study guidelines and length of studies.
Dr. Arnett concluded his presentation with thoughts on what needs to be done regarding the impact of wind energy facilities on wildlife. His proposed steps included: 1) better education of landowners, wind developers, scientists and politicians; 2) keeping the public informed which is extremely important; 3) wind energy developers sharing their pre-construction and mortality studies with scientists and agencies; 4) wind energy developers avoiding high risk areas; and 5) environmental impact studies that cover all forms of energy development.